During the coming year we will continue with some of the studies described in this report and initiate several new ones. Occasional livers contain a minor alkaline phosphatase (AP) which reacts with antisera against intestinal AP, but is of lower molecular weight than the major liver enzyme or the published molecular weight of the intestinal AP. We therefore intend to investigate the physicochemical properties of the intestinal enzyme(s) and to determine whether this AP also contains a minor low molecular weight component. Similar investigations will also be performed with placental AP since antisera against this enzyme cross react with the minor liver AP. We also intend to study the alkaline phosphatases of fetal livers to ascertain whether embryonic tissue contains the minor liver component, and hepatomas in order to compare our findings with those of Warnock and Reisman, who described a AP variant of liver in hepatomas. Our physicochemical and immunologic characterization of other tissue antigens will continue; investigations will include determinations of molecular weight, electrophoretic mobility and isoelectric point. The polymeric forms of liver ferritin will be purified and checked for their antigenic properties. We will proceed with our search of antibody activity against tissue antigens among monoclonal immunoglobulins; and of tissue antigens in concentrated sera and urines of various patients. During the last year we collected several osteogenic sarcomas and an intensive spudy of their antigens will be initiated.